Cleaning device and image forming apparatus

ABSTRACT

A cleaning device includes a controller configured to control cleaning of a conveyance roller by a web. The controller includes a separation and contact control unit, a conveyance roller rotation control unit, and a take-up control unit. The separation and contact control unit is configured to control a separation and contact mechanism so as to allow the web to be pressed to the conveyance roller when the conveyance roller is in a non-conveyable state. The conveyance roller rotation control unit rotates the conveyance roller in a state where the web is pressed to the conveyance roller. The take-up control unit is configured to allow the take-up roller to perform a take-up operation of taking up the web by rotatably driving the take-up roller plural times at a predetermined time interval within a cleaning time set in advance in a state where the conveyance roller is being rotated.

INCORPORATION BY REFERENCE

This application is based on Japanese Patent Application No. 2019-101712filed with the Japanese Patent Office on May 30, 2019 and JapanesePatent Application No. 2019-175348 filed with the Japanese Patent Officeon Sep. 26, 2019, the contents are incorporated by reference.

BACKGROUND Field of the Invention

The present disclosure relates to a cleaning device for cleaning aconveyance roller which conveys a sheet, and an image forming apparatuswhich includes the cleaning device.

Related Art

In an image forming apparatus such as a printer, a sheet is conveyed toa predetermined image forming position, and an image is formed on thesheet at the image forming position. Conventionally, there has beenknown a pair of resist rollers which is used for feeding a sheet to animage forming position. The pair of resist rollers each has a lengthcorresponding to a width of a sheet, and forms a nip portion throughwhich the sheet passes. When a distal end portion of the sheet isbrought into contact with the nip portion in a state where the rotationof the pair of resist rollers is stopped, skewing of the sheet isstraightened. Then, when the pair of resist rollers is rotated, thesheet is conveyed into the nip portion and, thereafter, the sheet is fedout (conveyed) in accordance with appropriate image forming timing atthe image forming position.

Conventionally, there has been known a cleaning device which removespaper dust adhering to a surface of each resist roller. In such acleaning device, a web which is wound in a roll shape is taken up by atake-up roller. Accordingly, a new web surface is brought into contactwith a surface of the resist roller so that paper dust is removed.

In the above-mentioned prior art, out of the pair of resist rollers, theweb is brought into contact with the surface of the resist rollerdisposed on a lower side, and the web cleans the surface. Each time theresist roller is cleaned by the web, a web take-up operation isperformed by the take-up roller, and a portion of the web which isbrought into contact with the resist roller changes.

SUMMARY

A cleaning device according to an aspect of the present disclosure iscapable of cleaning a surface of a conveyance roller that is rotatablysupported on an apparatus body of an image forming apparatus and isconfigured to convey a sheet. The cleaning device includes astrip-shaped web, a support roller, a take-up roller, a pressing roller,a separation and contact mechanism, and a controller. The web cleans thesurface of the conveyance roller by being brought into contact with thesurface of the conveyance roller. The support roller supports a rolledbody formed of the web. The take-up roller is rotatably driven, andtakes up the web while pulling out the web from the support roller. Thepressing roller is brought into contact with the web between the supportroller and the take-up roller, and presses the web to the conveyanceroller. The separation and contact mechanism separates the web from theconveyance roller and brings the web into contact with the conveyanceroller by changing a position of the pressing roller with respect to theconveyance roller. The controller controls cleaning of the conveyanceroller by the web.

The controller includes a conveyance state determination unit, aseparation and contact control unit, a conveyance roller rotationcontrol unit, and a take-up control unit. The conveyance statedetermination unit determines whether the conveyance roller is in eithera sheet conveyable state or a sheet non-conveyable state. The separationand contact control unit controls the separation and contact mechanismso as to allow the web to be pressed to the conveyance roller by thepressing roller when the conveyance roller is in the sheetnon-conveyable state. The conveyance roller rotation control unitrotates the conveyance roller in a state where the web is pressed to theconveyance roller. The take-up control unit allows the take-up roller toperform a take-up operation of taking up the web by rotatably drivingthe take-up roller plural times at a predetermined time interval withina cleaning time set in advance in a state where the conveyance roller isbeing rotated.

An image forming apparatus according to another aspect of the presentdisclosure includes: an apparatus body; a conveyance roller configuredto be rotatably supported on the apparatus body and to convey a sheet;an image forming unit configured to form an image on the sheet; and theabove-mentioned cleaning device configured to clean the conveyanceroller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an internal structureof an image forming apparatus according to an embodiment of the presentdisclosure;

FIG. 2 is a cross-sectional view of a pair of resist rollers, a cleaningunit of the image forming apparatus and the surrounding of these parts,and is also a cross-sectional view showing a state where the cleaningunit is disposed at a cleaning position;

FIG. 3 is a perspective view of the cleaning unit;

FIG. 4 is a perspective view of the cleaning unit;

FIG. 5 is a perspective view of the cleaning unit;

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5;

FIG. 7 is a perspective view of the cleaning unit and a web feed-outmechanism of the image forming apparatus;

FIG. 8 is a perspective view showing a state where a conveyance unitframe is detached from a body frame which forms a part of an apparatusbody of the image forming apparatus;

FIG. 9 is a perspective view of the conveyance unit frame;

FIG. 10 is a perspective view of the conveyance unit frame;

FIG. 11 is a perspective view of a cleaning unit rotating unit of theconveyance unit frame;

FIG. 12 is a cross-sectional view showing a state where the cleaningunit is to be mounted on the conveyance unit frame;

FIG. 13 is a cross-sectional view showing a state where the cleaningunit is mounted on the conveyance unit frame;

FIG. 14 is a cross-sectional view of the pair of resist rollers, thecleaning unit of the image forming apparatus and the surrounding ofthese parts, and is also a cross-sectional view showing a state wherethe cleaning unit is disposed at a mounting and removing position;

FIG. 15 is a cross-sectional view of the pair of resist rollers, thecleaning unit of the image forming apparatus and the surrounding ofthese parts, and is also a cross-sectional view showing a state wherethe cleaning unit is disposed at a separation position;

FIG. 16 is a block diagram showing the electrical configuration of theimage forming apparatus;

FIG. 17 is a timing chart when a resist lower roller is cleaned by a webof the cleaning unit;

FIG. 18 is a table showing conversion rate related information stored ina memory unit of a cleaning control part in a controller of the imageforming apparatus;

FIG. 19 is a table showing threshold-value related information stored inthe memory unit;

FIG. 20 is a graph showing the relationship between a cumulative valueof the number of times of solenoid operations and a web take-up amountfor each one solenoid operation; and

FIG. 21 is a table showing operation number setting information storedin the memory unit.

DETAILED DESCRIPTION

Hereinafter, a cleaning device and an image forming apparatus accordingto an embodiment of the present disclosure are described with referenceto drawings.

FIG. 1 is a schematic cross-sectional view showing an internal structureof an image forming apparatus 1 according to the embodiment of thepresent disclosure. The image forming apparatus 1 shown in FIG. 1 is anink jet recording apparatus which forms (records) an image on a sheet Sby ejecting ink droplets. The image forming apparatus 1 includes anapparatus body 10, a paper supply unit 20, a resist roller unit 30, abelt conveyance unit 40, an image forming unit 50, a curl correctionunit 60, and a maintenance unit 61.

The apparatus body 10 is a box-shaped housing that houses variousdevices for forming an image on the sheet S. In the apparatus body 10, afirst conveyance path 11, a second conveyance path 12, and a thirdconveyance path 13 which form a conveyance path of the sheet S areformed.

The paper supply unit 20 supplies the sheet S to the first conveyancepath 11. The paper supply unit 20 includes a paper supply cassette 21and a paper supply roller 22. The paper supply cassette 21 is detachablymounted on the apparatus body 10 and sheets S are stored in the papersupply cassette 21. The paper supply roller 22 is disposed on a rightside of an upper end portion of the paper supply cassette 21. The papersupply roller 22 conveys the sheet S stored in the paper supply cassette21 to a downstream side of the first conveyance path 11.

The sheet S supplied to the first conveyance path 11 is conveyed to theresist roller unit 30 disposed on a downstream end of the firstconveyance path 11 by a pair of first conveyance rollers 111 disposed onthe first conveyance path 11. A paper supply tray 24 is disposed on aright side surface of the apparatus body 10, and sheets S can be placedon an upper surface of the paper supply tray 24. The sheets S placed onthe paper supply tray 24 are fed out toward the resist roller unit 30 bythe paper supply roller 23.

The resist roller unit 30 is a device which conveys the sheet S conveyedby way of the first conveyance path 11 or the paper supply roller 23toward a conveyance belt 41 of the belt conveyance unit 40 in a sheetconveyance direction A1. The resist roller unit 30 and the beltconveyance unit 40 convey the sheet S at different positions. Details ofthe resist roller unit 30 are described later.

The sheet S conveyed by the resist roller unit 30 is conveyed by thebelt conveyance unit 40 in a sheet conveyance direction A2. The sheetconveyance directions A1 and A2 are leftward directions in FIG. 1.

The belt conveyance unit 40 is disposed below the image forming unit 50.The belt conveyance unit 40 conveys the sheet S conveyed by the resistroller unit 30 in the sheet conveyance direction A2 toward the curlcorrection unit 60 such that the sheet S passes below the image formingunit 50. The belt conveyance unit 40 includes the conveyance belt 41, afirst support roller 421, a second support roller 422, a third supportroller 423, a pair of fourth support rollers 424, and a suction unit 43.

The conveyance belt 41 is an endless belt having a predetermined widthin a front-rear direction and extending in a left-right direction. Theconveyance belt 41 is disposed so as to opposedly face the image formingunit 50, and conveys the sheet S in the sheet conveyance direction A2 onan outer peripheral surface 411. An image forming position where animage is formed on the sheet S by the image forming unit 50 is set on anorbital movement path of the conveyance belt 41.

The conveyance belt 41 is supported in an extended manner between and bythe first support roller 421, the second support roller 422, the thirdsupport roller 423, and the pair of fourth support rollers 424. Thesuction unit 43 is disposed inside the conveyance belt 41 which issupported in an extended manner as described above in a state where thesuction unit 43 opposedly faces an inner peripheral surface 412 of theconveyance belt 41. The first support roller 421 is rotatably driven bya drive motor (not shown), and allows the conveyance belt 41 to orbit ina predetermined orbital direction. The conveyance belt 41 has aplurality of suction holes penetrating the conveyance belt 41 in athickness direction from the outer peripheral surface 411 to the innerperipheral surface 412.

The suction unit 43 is disposed so as to opposedly face the imageforming unit 50 with the conveyance belt 41 interposed therebetween. Thesuction unit 43 brings the sheet S into close contact with the outerperipheral surface 411 of the conveyance belt 41 by generating anegative pressure between the sheet S held on the outer peripheralsurface 411 of the conveyance belt 41 and the conveyance belt 41. Thesuction unit 43 includes a belt guide member 431, a suction housing 432,a suction device 433, and an exhaust duct 434.

The belt guide member 431 guides the orbital movement of the conveyancebelt 41 in an interlocking manner with the rotation of the first supportroller 421 between the first support roller 421 and the second supportroller 422.

The suction unit 43 generates a suction force by sucking air from aspace above the conveyance belt 41 through a groove portion and athrough hole formed in the belt guide member 431 and the suction holesof the conveyance belt 41. Due to such a suction force, an airflow(suction air) toward the suction unit 43 is generated in a space formedabove the conveyance belt 41. When the sheet S is conveyed onto theconveyance belt 41 by the resist roller unit 30 and covers a part of theouter peripheral surface 411 of the conveyance belt 41, a suction force(negative pressure) acts on the sheet S, and the sheet S is brought intoclose contact with the outer peripheral surface 411 of the conveyancebelt 41.

The suction housing 432 is a box-shaped housing having an upper opening,and the suction housing 432 is disposed below the conveyance belt 41such that the upper opening is covered by the belt guide member 431. Thesuction housing 432 defines a suction space 432A in cooperation with thebelt guide member 431.

An opening portion 432B is formed in a bottom wall portion of thesuction housing 432, and the suction device 433 is disposedcorresponding to the opening portion 432B. The exhaust duct 434 isconnected to the suction device 433. The exhaust duct 434 is connectedto an exhaust port (not shown) formed in the apparatus body 10.

The image forming unit 50 is disposed above the belt conveyance unit 40.The image forming unit 50 forms an image by applying image formingprocessing to the sheet S which is conveyed in the sheet conveyancedirection A2 in a state where the sheet S is held on the outerperipheral surface 411 of the conveyance belt 41. In the thisembodiment, an image forming method of the image forming unit 50 is anink jet method, and an image is formed on the sheet S by ejecting inkdroplets.

The image forming unit 50 includes line heads 51 (51Bk, 51C, 51M, 51Y).The line head 51Bk ejects black ink droplets, the line head 51C ejectscyan ink droplets, the line head 51M ejects magenta ink droplets, andthe line head 51Y ejects yellow ink droplets. The line heads 51Bk, 51C,51M, and 51Y are arranged adjacently to each other from the upstreamside to the downstream side in the sheet conveyance direction A1.

The line heads 51 form an image on the sheet S by ejecting ink dropletson the sheet S conveyed in the sheet conveyance direction A2 in a statewhere the sheet S is held on the outer peripheral surface 411 of theconveyance belt 41. As a result, an image is formed on the sheet S.

The sheet S on which the image is formed is conveyed by the conveyancebelt 41, and is discharged (fed out) toward the curl correction unit 60while being guided by a sheet discharge guide unit 44. The curlcorrection unit 60 is disposed downstream of the conveyance belt 41 inthe sheet conveyance direction A2 with the sheet discharge guide unit 44sandwiched therebetween. The curl correction unit 60 corrects the curlof the sheet S on which the image is formed while conveying the sheet Sto the downstream side.

The sheet S whose curl has been corrected by the curl correction unit 60is fed out to the second conveyance path 12. The second conveyance path12 extends along a left side surface of the apparatus body 10. The sheetS fed out to the second conveyance path 12 is conveyed by a pair ofsecond conveyance rollers 121 disposed on the second conveyance path 12toward a paper discharge port 12A formed on a left side of the apparatusbody 10, and the sheet S is discharged onto a paper discharge unit 14from the paper discharge port 12A.

On the other hand, in a case where both-side printing is performed onthe sheet S, the sheet S on which the image forming processing of afirst surface (front surface) has been completed is fed out from thesecond conveyance path 12 to a sheet reversing unit 15. The sheetreversing unit 15 is a conveyance path branched from a middle portion ofthe second conveyance path 12, and is a part where the sheet S isreversed (switched back). The sheet S where the front surface and theback surface are reversed by the sheet reversing unit 15 is fed out tothe third conveyance path 13. The sheet S fed out to the thirdconveyance path 13 is reversely fed by a pair of third conveyancerollers 131 provided in the third conveyance path 13, and is suppliedagain onto the outer peripheral surface 411 of the conveyance belt 41 byway of the resist roller unit 30 in a state where the front surface andthe back surface of the sheet S are reversed. With respect to the sheetS supplied onto the outer peripheral surface 411 of the conveyance belt41 in a state where the front surface and the back surface of the sheetS are reversed as described above, the image forming processing isapplied to a second surface (back surface) on a side opposite to thefirst surface of the sheet S by the image forming unit 50 while beingconveyed by the conveyance belt 41. The sheet S on which both-sideprinting has been completed passes through the second conveyance path12, and is discharged onto the paper discharge unit 14 from the paperdischarge port 12A.

In the image forming apparatus 1, the inks are ejected from the lineheads 51 when the image forming processing for forming an image on thesheet S is performed. On the other hand, when maintenance processing forthe line heads 51 is performed during stoppage of the image formingprocessing applied to the sheet S, purge processing is performed fordischarging the pressurized inks from the line heads 51. The maintenanceprocessing for the line heads 51 is performed by the maintenance unit 61shown in FIG. 1. The maintenance unit 61 includes a cap unit 61B and awipe unit 61C mounted in a carriage 61A. Details of the configuration ofthe maintenance unit 61 and details of the maintenance processing forthe line heads 51 are described later.

FIG. 2 is a cross-sectional view of the pair of resist rollers, thecleaning unit 70 of the image forming apparatus 1 and the surrounding ofthese parts according to the present embodiment, and is across-sectional view showing a state where the cleaning unit 70 isdisposed at a cleaning position.

The above-described resist roller unit 30 has a resist housing 30H and apair of resist rollers consisting of a resist upper roller 31 and aresist lower roller 32 (conveyance rollers). The resist housing 30H ismounted on the apparatus body 10, and rotatably supports the resistupper roller 31 and the resist lower roller 32. The sheet S is conveyedinto a nip portion formed between the pair of resist rollers asindicated by an arrow in FIG. 2 in the resist housing 30H. The resistroller unit 30 has a resist driving unit 30M (see FIG. 16 describedlater) which rotatably drives the resist upper roller 31 and the resistlower roller 32.

The resist upper roller 31 is a roller disposed on an upper side out ofthe pair of resist rollers. The resist upper roller 31 is formed of ametal roller.

The resist lower roller 32 is a roller disposed on a lower side out ofthe pair of resist rollers. The resist lower roller 32 is formed of arubber roller, and a tetrafluoroethylene-perfluoroalkoxy ethylenecopolymer resin (PFA) tube is wound around (fitted in) an outerperipheral surface of the resist lower roller 32.

As shown in FIG. 2, a straight line L connecting the center of theresist upper roller 31 and the center of the resist lower roller 32 isinclined at an acute angle (for example, 10 degrees) with respect to avertical direction. In other words, the resist lower roller 32 isdisposed at the position displaced upstream in a conveyance direction ofthe sheet S with respect to the resist upper roller 31.

Further, the image forming apparatus 1 includes a cleaning device 7. Thecleaning device 7 can clean a surface of the resist lower roller 32. Thecleaning device 7 has the cleaning unit 70 and a movement mechanism 75(separation and contact mechanism; see FIG. 9). The movement mechanism75 has a function of moving the cleaning unit 70 between the cleaningposition (FIG. 2), a mounting and removing position (FIG. 14), and aseparation position (FIG. 15).

FIGS. 3 to 5 are perspective views of the cleaning unit 70 of the imageforming apparatus 1 according to the present embodiment. FIG. 6 is across-sectional view taken along line VI-VI in FIG. 5.

The cleaning unit 70 has a cleaning part 70A and a cleaning housing 70H.The cleaning part 70A has a shape extending along an axial direction ofthe resist lower roller 32, and is brought into contact with a surfaceof the resist lower roller 32 from below so as to clean the surface ofthe resist lower roller 32.

The cleaning housing 70H supports the cleaning part 70A. The cleaninghousing 70H has a front wall 701 and a rear wall 702, a connection wall703, a pair of unit fulcrum pins 70P, a sheet member 704, and a pair ofguide rollers 705. The front wall 701, the rear wall 702, and theconnection wall 703 of the cleaning housing 70H are made of a metalmaterial (magnetic material).

The front wall 701 and the rear wall 702 are disposed so as to opposedlyface each other in the front-rear direction (axial direction of theresist lower roller 32) and support the cleaning part 70A. Theconnection wall 703 connects the front wall 701 and the rear wall 702along the front-rear direction. The connection wall 703 has a side wall703A and a bottom wall 703B (FIGS. 5 and 6). A pair of front and rearribs 703T are formed on the bottom wall 703B in a protruding manner (seeFIGS. 12 and 13).

The pair of unit fulcrum pins 70P is formed on the front wall 701 andthe rear wall 702 in a protruding manner from outer surfaces of thefront wall 701 and the rear wall 702 in the front-rear directionrespectively. The unit fulcrum pins 70P are disposed on left lowerportions of the front wall 701 and the rear wall 702 respectively. Eachunit fulcrum pin 70P has a circular cylindrical shape in two stageswhere an outer diameter of the unit fulcrum pin 70P decreases toward adistal end portion.

The sheet member 704 is fixed to the bottom wall 703B so as to define aleft side surface of the cleaning unit 70 (FIG. 6). The sheet member 704prevents a collected matter such as paper dust collected by the cleaningunit 70 from scattering toward the belt conveyance unit 40 (FIG. 1).

The pair of guide rollers 705 is supported by the front wall 701 and therear wall 702 above the unit fulcrum pins 70P respectively, and eachguide roller 705 includes an outer peripheral surface which is rotatableabout a center axis parallel to the front-rear direction. The guiderollers 705 are disposed on right upper portions of the front wall 701and the rear wall 702 respectively. The pair of guide rollers 705 has afunction of guiding the cleaning unit 70 when the cleaning unit 70 movesto the mounting and removing position, the separation position, and thecleaning position described above.

The cleaning part 70A includes: a web W; a web driven roller 71 (supportroller) rotatably supported by the front wall 701 and the rear wall 702;a pressing roller 72; and a web drive roller 73 (take-up roller) (seeFIG. 6). The web W is formed of a strip-shaped member having a contactsurface capable of being brought into contact with the surface of theresist lower roller 32. The web W is formed of a cloth material such asa nonwoven fabric as an example. The web W comes into contact with thesurface of the resist lower roller 32, and thus cleaning the surface ofthe resist lower roller 32. In the present embodiment, as shown in FIG.6, a web roll WR which is a rolled body formed by winding the web Win aroll shape in advance is fitted on the web driven roller 71. Then, adistal end of the web W is caught by an outer peripheral surface of thepressing roller 72 and, thereafter, the distal end of the web W is fixedto an outer peripheral surface of the web drive roller 73.

The web driven roller 71 is a support roller for supporting the web rollWR which is a rolled body formed of the web W. The web drive roller 73is a roller which is rotatably driven, and is a take-up roller having adrive roller gear 713 as a drive input portion to which a rotationaldrive force is input. The web drive roller 73 takes up the web W whilepulling out the web W from the web driven roller 71 due to the rotationcorresponding to a rotational drive force inputted to the drive rollergear 713. The pressing roller 72 is brought into contact with a backsurface of the web W between the web driven roller 71 and the web driveroller 73, and presses the front surface of the web W to the resistlower roller 32. When the cleaning unit 70 is disposed at theabove-described cleaning position (FIG. 2), the pressing roller 72 isbrought into contact with the resist lower roller 32 with the web Wsandwiched therebetween. When the web W is pulled out from the webdriven roller 71 corresponding to the rotation of the web drive roller73, a portion of the web W which is brought into contact with the resistlower roller 32 by way of the pressing roller 72 changes.

As shown in FIG. 5, a state of the web roll WR which is supported by theweb driven roller 71 can be visually recognized from the outside of thecleaning unit 70 through an opening portion formed between the side wall703A and the bottom wall 703B. Accordingly, it is possible to preventthe cleaning unit 70 which is removed from the apparatus body 10 duringuse and where a feedable amount of the web W becomes small from beingerroneously mounted on the apparatus body 10.

The cleaning unit 70 also has a unit input gear 711 (FIG. 4), aninterlocking gear 711T, a transmission gear 712, and the above-describeddrive roller gear 713 (FIG. 6).

The unit input gear 711 is rotatably supported at a lower right endportion of the front wall 701. An input gear shaft 711S of the unitinput gear 711 penetrates the front wall 701 and extends to the inside(back side) of the front wall 701. The interlocking gear 711T is fixedto the input gear shaft 711S, and rotates integrally with the unit inputgear 711.

The transmission gear 712 is rotatably supported on an inner side of thefront wall 701, and engages with the interlocking gear 711T and thedrive roller gear 713 respectively. The drive roller gear 713 is a gearfixed to one end portion of the web drive roller 73. The drive rollergear 713 functions as a drive input portion to which a rotational driveforce for rotating the web drive roller 73 is inputted.

FIG. 7 is a perspective view of the cleaning unit 70 and a web feed-outmechanism 81 of the image forming apparatus 1 according to the presentembodiment. The cleaning device 7 further includes the web feed-outmechanism 81. The web feed-out mechanism 81 is mounted on the apparatusbody 10 of the image forming apparatus 1. The web feed-out mechanism 81has a function of feeding out the web W of the cleaning unit 70. The webfeed-out mechanism 81 is connected to the cleaning unit 70 by disposingthe cleaning unit 70 at the cleaning position. The web feed-outmechanism 81 has a solenoid 811, a third detection sensor 813, andtransmission gears 814 and 815.

The solenoid 811 generates a drive force for rotating the web driveroller 73. The solenoid 811 has an extendable and retractable shaft811S, and rotates a rotary arm 812. The extendable and retractable shaft811S extends and retracts with respect to a body of the solenoid 811.The rotary arm 812 is a rotary member which is rotatably supported bythe apparatus body 10. The solenoid 811 rotates the rotary arm 812 alongwith an extending and retracting operation of the extendable andretractable shaft 811S by supplying electricity to the solenoid 811, andoutputs a rotational force of the rotary arm 812 as a rotational driveforce for the drive roller gear 713 fixed to the web drive roller 73.The solenoid 811 is supported by a sheet-metal-made drive frame (notshown) which is disposed inside the apparatus body 10.

The rotary arm 812 is rotatably supported on a shaft 812S (FIG. 7)provided to the drive frame disposed inside the apparatus body 10. Theshaft 812S is supported by the drive frame such that the shaft 812S isrotatable about a rotation center axis extending in the front-reardirection. The rotary arm 812 has a first arm portion 812A and a secondarm portion 812B. The first arm portion 812A extends rightward from therotation center axis of the rotary arm 812. A distal end portion of thefirst arm portion 812A is connected to the extendable and retractableshaft 811S. The second arm portion 812B extends toward a side oppositeto the first arm portion 812A and downward from the rotation center axisof the rotary arm 812. A detection piece 812C is fixedly mounted on adistal end portion (lower end portion) of the second arm portion 812B. Agear portion 812T which can rotate integrally with the shaft 812S ismounted on a rear end portion of the shaft 812S.

Further, the web feed-out mechanism 81 has a first one-way clutch (notshown) and a second one-way clutch (not shown). The first one-way clutchis fixedly mounted in the rotary arm 812 and is fitted on the shaft812S. The second one-way clutch is fixed to the drive frame in a statewhere the second one-way clutch is disposed adjacently to the firstone-way clutch, and is fitted on the shaft 812S.

The third detection sensor 813 is fixed to a left end portion of a bodyof the solenoid 811. The third detection sensor 813 is a detection unitwhich detects the detection piece 812C when the detection piece 812C isdisposed in a predetermined detection region along with the rotation ofthe rotary arm 812.

The transmission gear 814 is rotatably supported by the apparatus body10, and engages with the gear portion 812T. The transmission gear 814 isformed of a two-stage gear. In the same manner, the transmission gear815 is rotatably supported by the apparatus body 10, and thetransmission gear 815 engages with a rear gear portion of the two-stagegear of the transmission gear 814, and engages with the above-describedunit input gear 711.

FIG. 7 shows a state where the extendable and retractable shaft 811S isretracted (contracted) with respect to the body of the solenoid 811.When the supplying of electricity to the solenoid 811 is stopped fromthe state shown in FIG. 7, the extendable and retractable shaft 811Sprotrudes (extends) from the body of the solenoid 811 so that the rotaryarm 812 rotates in a counterclockwise direction in FIG. 7 about theshaft 812S. At this stage of the operation, the rotary arm 812 isrotated relative to the shaft 812S by an action of the above-describedfirst one-way clutch so that there is no possibility that the shaft 812Srotates.

On the other hand, when electricity is supplied to the solenoid 811 totake up the web W by a predetermined amount, the extendable andretractable shaft 811S is contracted with respect to the body of thesolenoid 811. As a result, the rotary arm 812 rotates in a clockwisedirection in FIG. 7 about the shaft 812S. At this stage of theoperation, the shaft 812S rotates integrally with the rotary arm 812 bya predetermined angle by an action of the above-described first one-wayclutch. As a result, a rotational drive force is inputted from the gearportion 812T fixed to the shaft 812S to the unit input gear 711 by wayof the transmission gear 814 and the transmission gear 815. Then, therotational drive force is further transmitted, from the unit input gear711, to the interlocking gear 711T, the transmission gear 712, and thedrive roller gear 713 of the cleaning unit 70. As a result, the webdrive roller 73 rotates by a preset rotation angle, and the web W ismoved so as to be taken up by the web drive roller 73. As a result, aportion of the contact surface of the web W which opposedly faces theresist lower roller 32 changes. The third detection sensor 813 detectsthe detection piece 812C each time the rotary arm 812 rotates by onereciprocation and hence, it is detected that the unit input gear 711 hasrotated and the web W has been moved.

When the web W is moved so as to be taken up by the web drive roller 73,the supplying of electricity to the solenoid 811 is stopped, and theextendable and retractable shaft 811S protrudes again to the body of thesolenoid 811. At this stage of the operation, it is possible to preventthe shaft 812S from rotating in a reverse direction by an action of theabove-described second one-way clutch. Further, the one-way clutchmounted on a drive roller shaft 73S of the web drive roller 73 functionsso that it is possible to prevent the web drive roller 73 from rotatingin the reverse direction. By switching a state of supplying electricityto the solenoid 811 between an electricity supply state and anelectricity supply stop state, the extending and retracting operation ofthe extendable and retractable shaft 811S is performed. The rotary arm812 rotates corresponding to the extending and retracting operation ofthe extendable and retractable shaft 811S, and the web drive roller 73rotates corresponding to the rotation of the rotary arm 812.Accordingly, the web W is moved so as to be taken up by the web driveroller 73. As described above, in the present embodiment, it is possibleto feed out the web W from the web roll WR supported by the web drivenroller 71 by making use of a slight extending and retracting stroke ofthe extendable and retractable shaft 811S of the solenoid 811. Inanother embodiment, the web feed-out mechanism 81 may rotatably drivethe web driven roller 71 in addition to the web drive roller 73.

With reference to FIG. 7, a torque limiter 72T is mounted on a pressingroller shaft 72S of the pressing roller 72. There may be a case whereclogging of the sheet S occurs in the image forming apparatus 1 in astate where the web W (the pressing roller 72) of the cleaning device 7is brought into contact with the resist lower roller 32 and the sheet Sis sandwiched between the resist upper roller 31 and the resist lowerroller 32. In this case, a user attempts to remove the sheet S cloggedbetween the resist upper roller 31 and the resist lower roller 32 byopening a predetermined cover of the apparatus body 10 of the imageforming apparatus 1, and by pulling out the sheet S in a directionopposite to a direction indicated by an arrow in FIG. 2. At this stageof the operation, when a force for pulling out the sheet S istransmitted from the resist lower roller 32 to the pressing roller 72,the web W is excessively fed out from the pressing roller 72 toward theweb drive roller 73. In the present embodiment, since the torque limiter72T is mounted on the pressing roller shaft 72S, when a suddenrotational force is applied to the pressing roller 72, the rotation ofthe pressing roller 72 is locked and hence, feeding out of the web W canbe prevented.

The movement mechanism 75 (FIG. 2) moves the cleaning unit 70 among thecleaning position (FIG. 2), the mounting and removing position below thecleaning position (FIG. 14), and the separation position (FIG. 15)located between the cleaning position and the mounting and removingposition. The movement mechanism 75 allows the pressing roller 72 of thecleaning part 70A to be brought into contact with the resist lowerroller 32 by way of the web W at the cleaning position. The movementmechanism 75 allows the cleaning part 70A to be disposed below theresist lower roller 32 in a separated manner at the mounting andremoving position, and allows the cleaning unit 70 to be mounted on orto be removed from the apparatus body 10 at the mounting and removingposition. At the separation position, the cleaning part 70A is disposedbelow the resist lower roller 32 in a separated manner, and theconnection between the cleaning unit 70 and the above-described webfeed-out mechanism 81 is released.

The movement mechanism 75 functions as a separation and contactmechanism which changes the position of the pressing roller 72 withrespect to the resist lower roller 32 by moving the cleaning unit 70,and thus separating the web W and the resist lower roller 32 from eachother or bringing the web W and the resist lower roller 32 into contactwith each other. The movement mechanism 75 moves the cleaning unit 70 tothe cleaning position, and thus bringing the web W into contact with theresist lower roller 32 due to pressing of the pressing roller 72.Further, the movement mechanism 75 moves the cleaning unit 70 to theseparation position, and thus disposing the pressing roller 72 below theresist lower roller 32 in a separated manner. Accordingly, the web W isseparated from the resist lower roller 32.

FIG. 8 is a perspective view showing a state where a conveyance unitframe 40H is removed from the body frame 100 which forms the apparatusbody 10 of the image forming apparatus 1 according to the presentembodiment. FIGS. 9 and 10 are perspective views of the conveyance unitframe 40H.

The belt conveyance unit 40 shown in FIG. 1 further includes theconveyance unit frame 40H. The conveyance unit frame 40H integrallysupports the conveyance belt 41, the first support roller 421, thesecond support roller 422, the third support roller 423, the pair offourth support rollers 424, and the suction unit 43. The conveyance unitframe 40H can be mounted in the body frame 100 of the apparatus body 10in a first direction (rearward direction) parallel to the front-reardirection (the axial direction of the resist lower roller 32), and canbe removed from the body frame 100 along a second direction (frontwarddirection) opposite to the first direction.

With reference to FIGS. 9 and 10, the conveyance unit frame 40H includesa front frame 401, a rear frame 402, a left frame 403, a first rightframe 404A, a second right frame 404B, and a pair of front and rearmagnets 404C, and a pair of left and right rail portions 40R.

The front frame 401 is a frame disposed on a front surface portion ofthe conveyance unit frame 40H. A front cover 401A is mounted on thefront frame 401. The front cover 401A forms a part of the front surfaceportion of the apparatus body 10. The rear frame 402 is a frame disposedon a rear surface portion of the conveyance unit frame 40H, and isdisposed so as to opposedly face the front frame 401 in the front-reardirection. The left frame 403 is disposed on a left end portion of theconveyance unit frame 40H, and connects the front frame 401 and the rearframe 402 to each other along the front-rear direction. The first rightframe 404A and the second right frame 404B are disposed on the right endportion of the conveyance unit frame 40H, and connect the front frame401 and the rear frame 402 to each other along the front-rear direction.The first right frame 404A is disposed along an upper surface portion ofthe conveyance unit frame 40H, and the second right frame 404B isdisposed below the first right frame 404A. Both end portions of thefirst right frame 404A and both end portions of the second right frame404B in the front-rear direction are respectively connected to eachother along a vertical direction by a pair of side plates (not shown)which is disposed inside the front frame 401 and the rear frame 402. Asa result, a rectangular frame structure is formed by the first rightframe 404A, the second right frame 404B, and the above-described pair ofside plates.

The left and right rail portions 40R which form a pair are rail portionsfor allowing the conveyance unit frame 40H to move in a slidable mannerin the front-rear direction with respect to the body frame 100. In FIGS.9 and 10, only the right rail portion 40R is described. However, asimilar rail portion 40R is disposed also at the left end portion of theconveyance unit frame 40H. The pair of magnets 404C are magnets disposedon an upper surface portion of the second right frame 404B at intervalsin the front-rear direction. The pair of magnets 404C has a function ofholding the cleaning unit 70.

As shown in FIGS. 9 and 10, a conveyance unit mounting portion 40A isformed, on the conveyance unit frame 40H, closer to the left side thanthe first right frame 404A and the second right frame 404B are. Theconveyance belt 41, the first support roller 421, the second supportroller 422, the third support roller 423, the pair of fourth supportrollers 424, the suction unit 43, and the like are disposed in theconveyance unit mounting portion 40A. On the other hand, a cleaning unitmounting portion 40B is disposed in a space between the first rightframe 404A and the second right frame 404B. The cleaning unit mountingportion 40B allows the above-described cleaning unit 70 disposed at themounting and removing position to be mounted on the cleaning unitmounting portion 40B, and houses the cleaning unit 70. The cleaning unitmounting portion 40B forms a part of the movement mechanism 75.

Further, the conveyance unit frame 40H has a cleaning unit rotating unit45 and a rotation input gear 40G. FIG. 11 is a perspective view of thecleaning unit rotating unit 45 of the conveyance unit frame 40Haccording to the present embodiment.

The cleaning unit rotating unit 45 is supported by the pair of sideplates just below the first right frame 404A. The cleaning unit rotatingunit 45 includes a rotary shaft 451, a pair of front and rear bearings451S, a rotary gear 452, a pair of front and rear lever support portions453, and a pair of front and rear rotary levers 454.

The rotary shaft 451 is rotatably supported by the pair of side platesby way of the pair of front and rear bearings 451S. The rotary shaft 451extends along the front-rear direction (the axial direction of theresist lower roller 32) and forms a center axis (first center axis) inthe rotation of the pair of rotary levers 454. The rotary gear 452 is agear fixed to a rear end portion of the rotary shaft 451, and engageswith the rotation input gear 40G.

The pair of front and rear rotary levers 454 is disposed in the cleaningunit mounting portion 40B. The rotary levers 454 support the cleaninghousing 70H such that the rotary levers 454 sandwich the cleaninghousing 70H of the cleaning unit 70 from both sides in the front-reardirection (the axial direction of the resist lower roller 32). Pinreceiving portions 454P are formed on the pair of front and rear rotarylevers 454 respectively. The pin receiving portions 454P have a functionof receiving the unit fulcrum pin 70P (FIGS. 3 and 4) of the cleaningunit 70 along a direction orthogonal to the front-rear direction (theaxial direction of the resist lower roller 32) and a function ofrotatably supporting the unit fulcrum pin 70P. The pair of front andrear lever support portions 453 is fixed to the rotary shaft 451 suchthat the front and rear lever support portions 453 hold the pair ofrotary levers 454 respectively.

Further, the cleaning device 7 has a rotation drive unit 75K. Therotation drive unit 75K forms a part of the movement mechanism 75. Therotation drive unit 75K rotates the pair of rotary levers 454 about thecenter axis of the rotary shaft 451. Along with such rotation, thecleaning unit 70 moves between the cleaning position and the mountingand removing position by way of the separation position in a state wherethe pair of unit fulcrum pins 70P is pivotally supported on the pair ofpin receiving portions 454P. The center axis is disposed above the pinreceiving portion 454P in FIG. 2. Further, the rotation drive unit 75Krotates the pair of rotary levers 454 while allowing the pair of unitfulcrum pins 70P to rotate relative to the pair of pin receivingportions 454P such that the cleaning unit 70 maintains an orientationwhere the cleaning part 70A (web W) of the cleaning unit 70 facesupward.

The rotation drive unit 75K has a unit driving unit 80 (FIG. 2) inaddition to the above-described cleaning unit rotating unit 45. The unitdriving unit 80 generates a drive force for rotating the rotary shaft451 of the cleaning unit rotating unit 45 about the center axis of therotary shaft 451. With reference to FIG. 2, the unit driving unit 80includes a motor (not shown) including a drive motor output shaft 801, apulse plate 802, a first detection sensor 803, a second detection sensor804, and a unit drive output gear 805 (FIG. 14).

The pulse plate 802 is fixed to the drive motor output shaft 801, androtates integrally with the drive motor output shaft 801. The firstdetection sensor 803 detects a rotation amount of the pulse plate 802.Specifically, the first detection sensor 803 includes a light emittingpart for emitting detection light, and a light receiving part forreceiving the detection light. A plurality of slits which open atintervals along the rotation direction of the pulse plate 802 are formedin the pulse plate 802. Along with the rotation of the pulse plate 802,the detection light is blocked by the slits, and the light receivingpart outputs a signal corresponding to a waveform of the detection lightand hence, a rotation amount of the drive motor output shaft 801 (thepair of rotary levers 454) is detected.

The second detection sensor 804 is formed of a publicly known PI sensor,and detects that the cleaning unit 70 is disposed at the cleaningposition shown in FIG. 2. In the present embodiment, when a part of thecleaning housing 70H of the cleaning unit 70 enters between the lightemitting part and the light receiving part of the second detectionsensor 804, the second detection sensor 804 detects the cleaning unit70.

The unit drive output gear 805 transmits a rotational drive forcegenerated by the motor of the unit driving unit 80 to the rotation inputgear 40G of the cleaning unit rotating unit 45. In the presentembodiment, when the conveyance unit frame 40H is mounted on the bodyframe 100, the rotation input gear 40G and the unit drive output gear805 engage with each other, and a rotational drive force can betransmitted.

FIG. 12 is a cross-sectional view showing a state where the cleaningunit 70 is to be mounted on the conveyance unit frame 40H according tothe present embodiment. FIG. 13 is a cross-sectional view showing astate where the cleaning unit 70 is mounted on the conveyance unit frame40H. FIG. 14 is a cross-sectional view of the pair of resist rollers,the cleaning unit 70 of the image forming apparatus 1 and thesurrounding of these parts, and is also a cross-sectional view showing astate where the cleaning unit 70 is disposed at a mounting and removingposition. FIG. 15 is a cross-sectional view of the pair of resistrollers, the cleaning unit 70 of the image forming apparatus 1 and thesurrounding of these parts, and is also a cross-sectional view showing astate where the cleaning unit 70 is disposed at the separation position.

With reference to FIG. 14, the movement mechanism 75 further includes aguide portion 100G. The guide portion 100G allows the pair of guiderollers 705 to be brought into contact with the guide portions 100Galong with the rotation of the pair of rotary levers 454 about the firstcenter axis, and guides the cleaning unit 70 between the cleaningposition and the mounting and removing position. The guide portion 100Ghas a pair of front and rear first guide surfaces 101R and a pair offront and rear second guide surfaces 102R. The pair of front and rearfirst guide surfaces 101R is formed of left side surfaces of a pair offront and rear guide frames 101 which the body frame 100 includes. Thefirst guide surface 101R is inclined such that the first guide surface101R guides the cleaning unit 70 (guide roller 705) rightward as thefirst guide surface 101R extends upward. In the same manner, the pair offront and rear second guide surfaces 102R is formed of parts of the pairof front and rear resist frames which the body frame 100 includes. Thesecond guide surface 102R is slightly inclined such that the secondguide surface 102R guides the cleaning unit 70 (guide roller 705)leftward as the second guide surface 102R extends upward.

The movement mechanism 75 has a pair of front and rear positioningportions 102S. The positioning portion 102S is brought into contact withthe guide roller 705 of the cleaning unit at the cleaning position andthus positioning the cleaning unit 70 such that the web W of thecleaning part 70A can clean the resist lower roller 32. As shown in FIG.14, the positioning portion 102S is connected to the second guidesurface 102R, and has an arc shape which extends along an outerperipheral surface of the guide roller 705. In FIG. 14, with respect tothe pair of front and rear first guide surfaces 101R, the pair of frontand rear second guide surfaces 102R, and the pair of front and rearpositioning portions 102S, the respective members on a rear side areshown.

As shown in FIG. 8, when the conveyance unit frame 40H is pulled outfrontward from the body frame 100 of the apparatus body 10, an operatorcan mount the cleaning unit 70 on the cleaning unit mounting portion 40Bof the conveyance unit frame 40H. As shown in FIG. 12, the pair ofrotary levers 454 is disposed so as to extend downward from the rotaryshaft 451. The pin receiving portion 454P has a shape obtained bycutting out a right side portion of the rotary lever 454 obliquelyleftward and downward. Accordingly, the operator can insert and fit thepair of left and right unit fulcrum pins 70P of the cleaning unit 70into the pin receiving portions 454P from above while holding the sidewall 703A and the bottom wall 703B (FIG. 6) of the cleaning unit 70(FIG. 13). At this stage of the operation, the above-described unitinput gear 711 is disposed behind the unit fulcrum pin 70P on a frontside of the cleaning unit 70. The unit fulcrum pin 70P on a rear side ofthe cleaning unit 70 is fitted into the pin receiving portion 454P.

When the pair of unit fulcrum pins 70P is fitted into the pin receivingportions 454P by the operator, the bottom wall 703B of the cleaninghousing 70H is disposed so as to opposedly face the pair of magnets404C, and the pair of ribs 703T is respectively brought into contactwith the upper surface portion of the second right frame 404B. As aresult, in addition to the pair of rotary levers 454, the cleaning unit70 is held by the second right frame 404B by a magnetic field generatedby the pair of magnets 404C. Accordingly, even when the operator leaveshis hand from the cleaning unit 70, it is possible to prevent thecleaning unit 70 from being removed from the conveyance unit frame 40H.

As described above, when the cleaning unit 70 is mounted on the cleaningunit mounting portion 40B (mounting and removing position) of theconveyance unit frame 40H, the operator inserts the conveyance unitframe 40H into the body frame 100. As a result, the cleaning unit 70 isinserted into the body frame 100, and the rotation input gear 40G of theconveyance unit frame 40H engages with the unit drive output gear 805 ofthe unit driving unit 80 in the body frame 100. At this stage of theoperation, the pair of front and rear guide rollers 705 of the cleaningunit 70 is disposed so as to oppositely face the first guide surfaces101R of the pair of front and rear guide portions 100G at predeterminedintervals in the left-right direction.

As shown in FIG. 14, when the cleaning unit 70 disposed at the mountingand removing position is viewed from a direction parallel to the axialdirection of the resist lower roller 32, a center (P2) of the unitfulcrum pin 70P supported by the pin receiving portion 454P is disposedbelow a center axis (P1) of the rotary shaft 451 and on a right side(one end side in a width direction) of the center axis (P1) of therotary shaft 451. A center of gravity (J) of the cleaning unit 70 isdisposed on a right side of the unit fulcrum pin 70P. In the presentembodiment, the pressing roller 72 includes the heavy pressing rollershaft 72S made of a metal material. Accordingly, the center of gravity(J) of the cleaning unit 70 is offset to a right side portion of thecleaning unit 70 so as to be positioned more on a right side than acenter (P4) of the pressing roller 72. Further, a center (P3) of themagnet 404C in the left-right direction (width direction) is disposed ona right side (distal end side in a moving direction of the cleaning unit70 in the left-right direction) of the center (P2) of the unit fulcrumpin 70P.

When the rotary shaft 451 of the cleaning unit rotating unit 45 isrotated from the state shown in FIG. 14 by a drive force of the unitdriving unit 80, the pair of rotary levers 454 is rotated correspondingto the rotation of the rotary shaft 451. At this stage of the operation,a left end portion of the bottom wall 703B moves upward along with themovement of the unit fulcrum pin 70P. As a result, a distance betweenthe left end portion of the bottom wall 703B and the magnet 404C isincreased and hence, an effect of a magnetic restraining force generatedby the magnet 404C becomes small whereby the bottom wall 703B of thecleaning unit 70 can be easily removed from the magnet 404C. Then, whenthe cleaning unit 70 is tilted rightward about the unit fulcrum pin 70Pdue to its own weight, the pair of guide rollers 705 is brought intocontact with the first guide surfaces 101R of the pair of guide portions100G respectively.

Thereafter, when the pair of rotary levers 454 further rotatescorresponding to the rotation of the rotary shaft 451, the cleaning unit70 moves upward and rightward while the pair of guide rollers 705 isguided by the first guide surface 101R. At this stage of operation, arotation trajectory of the rotary lever 454 and a movement trajectory ofthe cleaning unit 70 guided by the first guide surface 101R aredifferent from each other. In the present embodiment, the pair of unitfulcrum pins 70P of the cleaning unit 70 is supported by the pinreceiving portion 454P of the rotary lever 454 so as to be rotatablerelative to the pin receiving portion 454P. Accordingly, the orientationof the cleaning unit 70 can be changed along with the upward movement ofthe cleaning unit 70 and hence, the cleaning unit 70 can smoothly risecorresponding to the rotation of the rotary lever 454.

In a state shown in FIG. 15, the pair of guide rollers 705 istransferred from the first guide surfaces 101R to the second guidesurfaces 102R. Then, when the pair of rotary levers 454 further rotatescorresponding to the rotation of the rotary shaft 451, the pair of guiderollers 705 is brought into contact with and is fitted in the pair ofpositioning portions 102S. At this stage of the operation, as shown inFIG. 2, the pressing roller 72 of the cleaning part 70A of the cleaningunit 70 is brought into contact with the resist lower roller 32 frombelow along the straight line L which connects the center of the resistupper roller 31 and the center of the resist lower roller 32 to eachother. When the cleaning unit 70 reaches the cleaning position shown inFIG. 2 in this manner, the pressing roller 72 presses the web W to theresist lower roller 32 and hence, paper dust, inks, and the likeadhering to the surface of the resist lower roller 32 can be removed bycleaning. In the orientation of the cleaning unit 70 disposed at thecleaning position shown in FIG. 2, the center of gravity (the pressingroller 72) of the cleaning unit 70 is disposed just above the unitfulcrum pin 70P and hence, the orientation of the cleaning unit 70 atthe cleaning position can be maintained in a stable manner.

In the present embodiment, using the mounting and removing positionshown in FIG. 14 as the reference, the first detection sensor 803detects a rotation amount of rotation of the pulse plate 802 so that anamount of rotation of the rotary lever 454, that is, the position of thecleaning unit 70 (cleaning position, separation position) is detected.When the second detection sensor 804 detects the cleaning housing 70H,it is detected that the cleaning unit 70 has reached the cleaningposition.

Next, a control system of the image forming apparatus 1 and the cleaningdevice 7 according to the present embodiment is described with referenceto a block diagram shown in FIG. 16. The image forming apparatus 1further includes a controller 90.

The controller 90 is formed of, for example, a microcomputer in which amemory device such as a read only memory (ROM) for storing a controlprogram and a flash memory for temporarily storing data is incorporated.The controller 90 controls an operation of the image forming apparatus 1including the cleaning device 7 by reading out the control program. Thecontroller 90 includes an image forming control unit 90G, a maintenancecontrol unit 90M, and a cleaning control unit 90C.

The image forming control unit 90G mainly controls a sheet conveyanceoperation of the belt conveyance unit 40 and an image forming operationof the image forming unit 50, and executes image forming processing forthe sheet S.

The maintenance control unit 90M executes maintenance processing for theline head 51 by controlling a purge mechanism 50P and a maintenanceoperation mechanism 61M when the operation of the image formingprocessing for the sheet S is stopped. The maintenance processing forthe line head 51 includes cap processing, purge processing, and wipingprocessing.

The cap processing is processing for covering a cap on the line head 51.The maintenance control unit 90M executes the cap processing by mainlycontrolling the maintenance operation mechanism 61M. The maintenanceoperation mechanism 61M moves the cap unit 61B by moving the carriage61A in the maintenance unit 61 (FIG. 1) between a retracted positionwhere the cap unit 61B is retracted in a horizontal direction(left-right direction) with respect to the image forming unit 50 and amaintenance position vertically below the image forming unit 50. At thetime of moving the cap unit 61B from the retracted position to themaintenance position, before moving the cap unit 61B, the maintenanceoperation mechanism 61M lowers the belt conveyance unit 40 verticallydownward from the position just below the image forming unit 50. Whenthe cap unit 61B is disposed at the maintenance position, themaintenance operation mechanism 61M lifts the cap unit 61B verticallyupward. As a result, the cap unit 61B is brought into contact with anink ejection surface of the line head 51 and hence, the cap unit 61B iscovered by the cap.

The purge processing is processing for forcibly ejecting inkspressurized from the line head 51 for removing bubbles, foreign matters,thickened inks and the like in the ink ejection nozzles of the line head51. The wiping processing is processing for wiping ink droplets adheringto the ink ejection surface of the line head 51 after the purgeprocessing is performed.

The maintenance operation mechanism 61M moves the wipe unit 61C betweena retracted position where the wipe unit 61C is retracted in ahorizontal direction with respect to the image forming unit 50 and amaintenance position vertically below the image forming unit 50 bymoving the carriage 61A. At the time of moving the wipe unit 61C fromthe retracted position to the maintenance position, a state ismaintained where the cap unit 61B which is supported above the wipe unit61C in the carriage 61A is at the retracted position. Further, at thetime of moving the wipe unit 61C from the retracted position to themaintenance position, before moving the wipe unit 61C, the maintenanceoperation mechanism 61M lowers the belt conveyance unit 40 verticallydownward from the position just below the image forming unit 50. Whenthe wipe unit 61C is disposed at the maintenance position, themaintenance operation mechanism 61M lifts the wipe unit 61C verticallyupward. Then, the maintenance control unit 90M executes the purgeprocessing for the line head 51 by controlling the purge mechanism 50P.Further, the maintenance control unit 90M executes the wiping processingfor the line head 51 by moving a blade unit of the wipe unit 61C bycontrolling the maintenance operation mechanism 61M.

The cleaning control unit 90C forms a part of the cleaning device 7, andcontrols cleaning of the resist lower roller 32 by the cleaning unit 70using the web W. In the present embodiment, the cleaning control unit90C controls cleaning of the resist lower roller 32 by the cleaning unit70 based on a conveyed sheet number of both-surface image forming sheetsS where image forming processing is applied to both the first surface(front surface) and the second surface (back surface) with respect tothe sheets S conveyed by the resist roller unit 30. The cleaning controlunit 90C controls cleaning of the resist lower roller 32 by the cleaningunit 70 at the time of stopping the image forming processing on thesheet S and when the resist lower roller 32 is in a sheet Snon-conveyable state.

A sheet S on which an image is formed on the first surface in theboth-surface image forming processing (both-side printing), as describedpreviously, passes the sheet reversing unit 15 and the third conveyancepath 13, and is conveyed into the resist roller unit 30 again in a statewhere the front surface and the back surface of the sheet S arereversed. At this stage of the operation, when the ink of the imageformed on the first surface adheres to a surface of a PFA tube of theresist lower roller 32, the ink adheres to a distal end portion of thenext sheet S from the resist lower roller 32, and the sheet is stained.Further, when the ink adhering to the resist lower roller 32 istransferred to the resist upper roller 31, the ink adheres to a firstsurface of the next sheet S so that an image defect occurs.

In view of the above, in the present embodiment, the cleaning controlunit 90C disposes the cleaning unit 70 at the cleaning position during acleaning time CLT (FIG. 17) set in advance corresponding to theexecution of both-side printing, and disposes the cleaning unit 70 atthe separation position at the time of performing one-side printing.That is, the cleaning control unit 90C disposes the cleaning unit 70 atthe cleaning position within the cleaning time CLT, and disposes thecleaning unit 70 at the separation position during other time periods.As a result, the web roll WR having a limited length can performcleaning of the resist lower roller 32 for a long time, and the web rollWR can be made compact and hence, a size of the cleaning device 7 can bemade small.

Further, when an image is formed under a condition that the surface ofthe resist lower roller 32 is minimally stained such as one-sideprinting, the cleaning unit 70 is disposed at the separation position.Due to such an operation, a load imposed on the resist lower roller 32generated by contacting of the cleaning part 70A with the resist lowerroller 32 can be reduced, and it is possible to suppress unnecessaryfeeding of the web W.

A control of the cleaning control unit 90C is described with referenceto FIGS. 17 to 21 in addition to FIG. 16. FIG. 17 is a timing chart atthe time of cleaning the resist lower roller 32 by the web W of thecleaning unit 70. FIG. 18 is a table showing conversion rate relatedinformation J1 stored in a memory unit 99 of the cleaning control unit90C. FIG. 19 is a table showing threshold-value related information J2stored in the memory unit 99. FIG. 20 is a graph showing therelationship between a cumulative value of the number of times ofoperation of the solenoid 811 and a web take-up amount for eachoperation of the solenoid 811. FIG. 21 is a table showing operationnumber setting information J3 stored in the memory unit 99.

As shown in FIG. 16, the cleaning control unit 90C includes a conveyedsheet number determination unit 91, a conveyance state determinationunit 92, a separation and contact control unit 93, a resist rotationcontrol unit 94 (conveyance roller rotation control unit), and a take-upcontrol unit 95, an operation number determination unit 96, a web enddetermination unit 97, an information generation unit 98, and the memoryunit 99.

The memory unit 99 stores information which is referred at the time ofcontrolling cleaning of the resist lower roller 32 by the web W of thecleaning unit 70. The memory unit 99 stores the conversion rate relatedinformation J1 shown in FIG. 18, the threshold-value related informationJ2 shown in FIG. 19, and the operation number setting information J3shown in FIG. 21 respectively.

The conversion rate related information J1 shown in FIG. 18 isinformation indicating a conversion rate for converting a size of thesheet S into the conveyed sheet number of the sheets S for each size ofthe sheet S, and is information where sheet size information J11 andconversion rate information J12 are associated with each other.

The sheet size information J11 is information indicating a size of thesheet S. A size of the sheet S is represented by, for example, “A4 size”or “A3 size”. The conversion rate information J12 is informationindicating a conversion rate related to the conveyed sheet number of thesheets S conveyed by the resist roller unit 30. The conversion rateregistered in the conversion rate information J12 is set to have alarger value as the size of the sheet S registered in the sheet sizeinformation J11 is increased. For example, with respect to sizes “SS1”and “SS2” of the sheet S registered in the sheet size information J11,assume a case where, “SS1” indicates “A4 size” and “SS2” indicates “A3size”. In this case, with respect to the conversion rates “CR1” and“CR2” registered in the conversion rate information J12, “CR2”associated with “SS2” indicates a larger value than “CR1” associatedwith “SS1”. For example, when the conversion rate “CR1” is “1”, theconversion rate “CR2” is “2”. In this case, when one “A4 size” sheet Sis conveyed by the resist roller unit 30, the conveyed sheet number ofthe sheet S is corrected as “1”. On the other hand, when one “A3 size”sheet S is conveyed by the resist roller unit 30, the conveyed sheetnumber of the sheets S is corrected as “2”. The conversion rate relatedinformation J1 is referred by the conveyed sheet number determinationunit 91 described later.

The threshold-value related information J2 shown in FIG. 19 isinformation indicating a conveyance determination threshold value whichis referred when the conveyed sheet number determination unit 91determines the conveyed sheet number of the sheets S conveyed by theresist roller unit 30. In the threshold-value related information J2,timing condition information J21, printing condition information J22,and conveyance determination threshold value information J23 areassociated with each other.

The timing condition information J21 is information indicating acondition of a timing at which the cleaning unit 70 is moved from theseparation position to the cleaning position by a drive force of theunit driving unit 80. As described above, the cleaning control unit 90Ccontrols cleaning of the resist lower roller 32 by the cleaning unit 70at the time of stopping the image forming processing on the sheet S andwhen the resist lower roller 32 is in a sheet S non-conveyable state.Accordingly, movement timing of the cleaning unit 70 registered in thetiming condition information J21 is formed of first timing and secondtiming at which the condition that the resist lower roller 32 is in asheet S non-conveyable state is satisfied. The first timing is setwithin a period from a point of time that a series of image formingprocessing on a continuous sheet S is finished to a point of time thatnext image forming processing is started. The second timing is setwithin a period during which maintenance processing on the line head 51is executed by the maintenance control unit 90M at the time of stoppingimage forming processing on the sheet S. In the example shown in FIG.19, in the timing condition information J21, information indicating thefirst timing is registered as “CT1”, and information indicating thesecond timing is registered as “CT2”.

The printing condition information J22 is information indicating aprinting condition of an image on the sheet S. The printing conditioninformation J22 is, for example, information indicating a printingratio. The printing condition information J22 is registered for eachmovement timing of the cleaning unit 70 indicated in the timingcondition information J21. In the example shown in FIG. 19, “CP1”, “CP2”and the like are registered as the printing condition information J22corresponding to respective “CT1” and “CT2” of the timing conditioninformation J21.

The conveyance determination threshold value information J23 isinformation indicating a conveyance determination threshold value whichthe conveyed sheet number determination unit 91 refers when the conveyedsheet number determination unit 91 determines the conveyed number of thesheets S conveyed by the resist roller unit 30. In the example shown inFIG. 19, “TT11” and “TT12” are registered as the conveyancedetermination threshold value information J23 for respective “CP1” and“CP2” of the printing condition information J22 corresponding to “CT1”of the timing condition information J21. Further, “TT21” and “TT22” areregistered as the conveyance determination threshold value informationJ23 for respective “CP1” and “CP2” of the printing condition informationJ22 corresponding to “CT2” of the timing condition information J21.

A different value is set as the conveyance determination threshold valueregistered in the conveyance determination threshold value informationJ23 corresponding to the movement timing of the cleaning unit 70registered in the timing condition information J21. For example, theconveyance determination threshold values “TT11” and “TT21” registeredin the conveyance determination threshold value information J23 arecompared with each other. In this case, the conveyance determinationthreshold value “TT11” associated with “CT1” which indicates the firsttiming in the timing condition information J21 is set to a value smallerthan the conveyance determination threshold value “TT21” associated with“CT2” which indicates the second timing in the timing conditioninformation J21. Further, the conveyance determination threshold valueregistered in the conveyance determination threshold value informationJ23 is set to a smaller value as the printing ratio registered in theprinting condition information J22 is increased.

The operation number setting information J3 shown in FIG. 21 isinformation indicating a solenoid operation number setting value whichis referred when the take-up control unit 95 described later sets thenumber of times of take-up operation of the web W by the web driveroller 73. The number of times of take-up operation of the web W by theweb drive roller 73 is equal to the number of times of operation of thesolenoid 811. In the operation number setting information J3, cumulativevalue information J31 and operation number setting value information J32are associated with each other.

The cumulative value information J31 is information which indicates acumulative value of the number of times of the take-up operation of theweb W by the web drive roller 73, that is, a cumulative value of thenumber of times of operation of the solenoid 811. The operation numbersetting value information J32 is information which indicates a set valueof the number of times of take-up operation of the web W by the webdrive roller 73 within the cleaning time CLT (FIG. 17) set in advance,that is, a set value of the number of times of the operation of thesolenoid 811 in one cleaning. The solenoid operation number settingvalue registered in the operation number setting value information J32is set to a smaller value as a cumulative value of the number of timesof operation of the solenoid 811 registered in the cumulative valueinformation J31 is increased.

The conveyed sheet number determination unit 91 monitors a conveyedsheet number of both-surface image forming sheets S with respect to thesheets S conveyed by the resist roller unit 30 in a state where thecleaning unit 70 is disposed at the separation position. Then, theconveyed sheet number determination unit 91 refers the threshold-valuerelated information J2 stored in the memory unit 99, and determineswhether or not a cumulative value of the conveyed sheet number ofboth-surface image forming sheets S has reached the conveyancedetermination threshold value indicated in the conveyance determinationthreshold value information J23. At this stage of the operation, theconveyed sheet number determination unit 91 refers the conversion raterelated information J1 stored in the memory unit 99, and corrects theconveyed sheet number based on a conversion rate indicated in theconversion rate information J12 corresponding to a size of aboth-surface image forming sheet S. Then, the conveyed sheet numberdetermination unit 91 determines whether or not a cumulative value ofthe corrected conveyed sheet number has reached the conveyancedetermination threshold value.

The conveyance state determination unit 92 determines whether or not acondition that defines the first timing and the second timing indicatedin the timing condition information J21 of the threshold-value relatedinformation J2 stored in the memory unit 99 is satisfied. With suchprocessing, the conveyance state determination unit 92 determineswhether the resist lower roller 32 of the resist roller unit 30 is ineither a sheet S conveyable state or a sheet S non-conveyable state. Theconveyance state determination unit 92 determines that the resist lowerroller 32 is in a sheet S non-conveyable state during a period from apoint of time that a series of image forming processing on a continuoussheet S is finished to a point of time that next image formingprocessing is started which is a condition that defines the firsttiming. Further, the conveyance state determination unit 92 determinesthat the resist lower roller 32 is in a sheet S non-conveyable stateduring a period where maintenance processing for the line head 51 isexecuted by the maintenance control unit 90M which is a condition thatdefines the second timing.

The separation and contact control unit 93 controls the unit drivingunit 80 so as to move the cleaning unit 70. Assume a case where it isdetermined that a cumulative value of the conveyed sheet number ofboth-surface image forming sheets S has reached the conveyancedetermination threshold value by the conveyed sheet number determinationunit 91, and it is determined that the resist lower roller 32 is in anon-conveyable state by the conveyance state determination unit 92. Inthis case, the separation and contact control unit 93 controls the unitdriving unit 80 to move the cleaning unit 70 from the separationposition to the cleaning position so as to allow the web W to be pressedto the resist lower roller 32 by the pressing roller 72. When thecleaning unit 70 is disposed at the cleaning position by driving theunit driving unit 80, the second detection sensor 804 detects thecleaning unit 70. When a predetermined first time t1 is elapsed from apoint of time that the cleaning unit 70 is detected by the seconddetection sensor 804, the separation and contact control unit 93 stopsdriving of the unit driving unit 80 (see FIG. 17). The first time t1 isset to 400 ms, for example.

The resist rotation control unit 94 controls the resist driving unit 30Min a state where the web W is pressed to the resist lower roller 32 inthe cleaning unit 70 disposed at the cleaning position, and rotates theresist upper roller 31 and the resist lower roller 32. The resistrotation control unit 94 drives the resist driving unit 30M after apredetermined second time t2 is elapsed from a point of time thatdriving of the unit driving unit 80 is stopped (see FIG. 17). The secondtime t2 is set to 100 ms, for example. By rotating the resist lowerroller 32 in a state where the web W is pressed to the resist lowerroller 32, the surface of the resist lower roller 32 can be cleaned bythe web W.

In the present embodiment, the resist rotation control unit 94 controlsthe resist driving unit 30M, and rotates the resist lower roller 32 at acleaning rotation speed lower than a conveying-time rotation speed ofthe resist lower roller 32 in a sheet S conveyable state. Although thedetails are described later, a take-up operation of the web W by the webdrive roller 73 based on an operation of the solenoid 811 is performedplural times at a predetermined time interval within the predeterminedcleaning time CLT (see FIG. 17). The resist rotation control unit 94sets the cleaning rotation speed within a range of from a speed equal toor higher than a first rotation speed at which one rotation of theresist lower roller 32 is enabled during a take-up standby period WPbetween each of the plurality of take-up operations to a speed equal toor lower than a second rotation speed which is a half of theconveying-time rotation speed. By setting a rotation speed of the resistlower roller 32 in a state where the web W is pressed to the resistlower roller 32 to a cleaning rotation speed lower than theconveying-time rotation speed, a contact time of the resist lower roller32 with the web W can be increased. Accordingly, cleaning of the resistlower roller 32 by the web W can be performed more effectively.

The take-up control unit 95 performs a control of switching a state ofsupplying electricity to the solenoid 811 between an electricity supplystate and an electricity supply stop state in a state where the resistlower roller 32 is being rotated. By controlling switching of the stateof supplying electricity to the solenoid 811 as described above, thetake-up control unit 95 allows the web drive roller 73 to perform thetake-up operation of the web W plural times at a predetermined timeinterval within the predetermined cleaning time CLT. The take-up controlunit 95 controls the switching of the state of supplying electricity tothe solenoid 811 after a predetermined third time t3 is elapsed from apoint of time that driving of the resist driving unit 30M is started(see FIG. 17). The third time t3 is set to 1000 ms, for example.Further, the cleaning time CLT is set to a value within a range of from10 seconds to 30 seconds, for example, based on a printing ratio or thelike of an image formed on the sheet S during a period in which theimage forming unit 50 executes the image forming processing.

In a state where the cleaning unit 70 is disposed at the cleaningposition, a web pressing nip portion is formed due to pressing of thepressing roller 72 to the resist lower roller 32. A nip width of the webpressing nip portion is set to a value which falls within a range offrom 2.5 mm to 5.0 mm, for example. The take-up control unit 95 sets atotal take-up amount of the web W taken up by the web drive roller 73due to a plurality of take-up operations within the cleaning time CLTsuch that the total take-up amount agrees with the nip width of the webpressing nip portion.

In cleaning the resist lower roller 32 by the web W, the take-up controlunit 95 allows the web drive roller 73 to perform the take-up operationof the web W corresponding to the rotation of the web drive roller 73plural times at a predetermined time interval within the cleaning timeCLT. Accordingly, a portion of the web W which is brought into contactwith the resist lower roller 32 can be changed plural times within onecleaning time CLT. Accordingly, even in a case where an ink or the likefor forming an image on the sheet S adheres to the resist lower roller32, the ink or the like can be removed from the resist lower roller 32with certainty and can be collected on the web W, and thus cleaning theresist lower roller 32 properly.

When the take-up operation of the web W by the web drive roller 73 isperformed by the operation of the solenoid 811, a rolled body formed ofthe web W is formed on the web drive roller 73. An outer diameter of therolled body formed of the web W formed on the web drive roller 73 isincreased each time the web drive roller 73 performs the take-upoperation corresponding to the operation of the solenoid 811. That is,the outer diameter of the rolled body formed of the web W formed on theweb drive roller 73 is increased as a cumulative value of the number oftimes of operation of the solenoid 811 corresponding to the number oftimes of the take-up operation of the web drive roller 73 is increased.When the outer diameter of the rolled body formed of the web W formed onthe web drive roller 73 is increased, a take-up amount of the web Wtaken up by the web drive roller 73 by one operation of the solenoid 811is increased (see FIG. 20). Accordingly, in a case where the number oftimes of take-up operation of the web drive roller 73, that is, thenumber of times of operation of the solenoid 811 within the cleaningtime CLT is set to be constant, the take-up amount of the web Wcorresponding to the rotation of the web drive roller 73 changescorresponding to a cumulative value of the number of times of operationof the solenoid 811.

In view of the above, the take-up control unit 95 is configured to becapable of executing monitoring processing, operation number settingprocessing, and take-up processing. In the monitoring processing, thetake-up control unit 95 monitors a cumulative value of the number oftimes of operation of the solenoid 811 and thus monitoring the number oftimes of take-up operation of the web W by the web drive roller 73.Further, in the operation number setting processing, the take-up controlunit 95 sets the number of times of take-up operation of the web W bythe web drive roller 73, that is, the number of times of operation ofthe solenoid 811 in one cleaning within the cleaning time CLT. Thetake-up control unit 95 refers the operation number setting informationJ3 stored in the memory unit 99, and sets the number of times ofoperation of the solenoid 811 in one cleaning corresponding to acumulative value of the number of times of operation of the solenoid 811such that a total take-up amount of the web W taken-up by the web driveroller 73 due to the take-up operation performed plural times within thecleaning time CLT becomes constant within a predetermined allowablerange. Then, in the take-up processing, the take-up control unit 95allows the solenoids 811 to perform an operation the number of timescorresponding to the number of times set in the operation number settingprocessing at a predetermined time interval within the cleaning timeCLT.

In the take-up processing, the take-up control unit 95 allows the webdrive roller 73 to perform the respective plural-time take-up operationsof the web W based on the operation of the solenoid 811 at equal timeintervals. Accordingly, a portion of the web W which is brought intocontact with the resist lower roller 32 can be changed plural times atequal time intervals within one cleaning time CLT.

When cleaning of the resist lower roller 32 by the web W within thecleaning time CLT is finished, the resist rotation control unit 94controls the resist driving unit 30M such that the rotation of theresist lower roller 32 continues within a predetermined rotationcontinuation time RCT from a point of time of the end of the cleaningtime CLT (see FIG. 17). Then, the separation and contact control unit 93controls the unit driving unit 80, and moves the cleaning unit 70 fromthe cleaning position to the separation position such that the web W isseparated from the resist lower roller 32 within the rotationcontinuation time RCT.

When the cleaning unit 70 is moved from the cleaning position to theseparation position by driving the unit driving unit 80, the detectionof the cleaning unit 70 by the second detection sensor 804 is released.When a predetermined fourth time t4 is elapsed from a point of time thatthe detection of the cleaning unit 70 by the second detection sensor 804is released, the resist rotation control unit 94 stops driving of theresist driving unit 30M (see FIG. 17). The fourth time t4 is set to 500ms, for example. Note that when the cleaning unit is disposed at theseparation position, the separation and contact control unit 93 stopsdriving of the unit driving unit 80.

As described above, after cleaning the resist lower roller 32 by the webW, the web W is separated from the resist lower roller 32 in a statewhere the rotation of the resist lower roller 32 is continued.Accordingly, paper dust, ink, and the like adhering to the resist lowerroller 32 can be removed from the resist lower roller 32 with morecertainty and can be collected on the web W.

The operation number determination unit 96 monitors the number of timesof operation of the solenoid 811 in response to the supplying ofelectricity, and determines whether or not a cumulative value of thenumber of times of operation of the solenoid 811 has reached apredetermined operation determination threshold value. The operationdetermination threshold value is set to a value which enables arecognition of a fact that a remaining amount of the web roll WRsupported by the web driven roller 71 has reached a predeterminedwarning remaining amount due to a take-up operation of the web W by theweb drive roller 73 based on an operation of the solenoid 811. Forexample, assume a case where a total length of the web roll WR is “5 m”and an average value of take-up amount of the web W by the web driveroller 73 based on one operation of the solenoid 811 is “3.75 mm”. Inthis case, theoretically, an end of the web W is exposed on the webdriven roller 71 when a cumulative value of the number of times ofoperation of the solenoid 811 reaches “1333”. However, in an actualpractice, as shown in FIG. 20, as a cumulative value of the number oftimes of operation of the solenoid 811 is increased, a take-up amount ofthe web W taken up by the web drive roller 73 by one operation of thesolenoid 811 is increased so that a take-up amount of the web W ischanged. In view of the above, a cumulative value “1300” which issmaller than a cumulative value “1333” which is the number of times ofoperation of the solenoid 811 at which it is theoretically estimatedthat the end of the web W is exposed on the web driven roller 71 is setas the operation determination threshold value.

In a case where a cumulative value of the number of times of operationof the solenoid 811 has reached the operation determination thresholdvalue, the web end determination unit 97 executes a web enddetermination processing for determining whether or not the end of theweb W is exposed on the web driven roller 71. The web end determinationunit 97 determines whether or not the end of the web W is exposed on theweb driven roller 71 based on the state of supplying electricity to thesolenoid 811 and the detection result of the third detection sensor 813.In a case where the detection result of the third detection sensor 813is not changed in spite of a fact that supplying of electricity to thesolenoid 811 is performed, the web end determination unit 97 determinesthat the end of the web W is exposed on the web driven roller 71.Accordingly, it is possible to precisely determine a fact that the endof the web W is exposed on the web driven roller 71 so that it isnecessary to exchange the web W, that is, it is necessary to exchangethe cleaning unit 70. Accordingly, in exchanging the cleaning unit 70,the web W can be entirely used up without wasting the web W with respectto the web roll WR supported by the web driven roller 71.

The information generation unit 98 generates information indicatingrespective determination results of the operation number determinationunit 96 and the web end determination unit 97. Assume a case where theoperation number determination unit 96 determines that a cumulativevalue of the number of times of operation of the solenoid 811 hasreached the operation determination threshold value. In this case, theinformation generation unit 98 generates web remaining amount warninginformation for notifying that a remaining amount of the web roll WRsupported by the web driven roller 71 has reached a predeterminedwarning remaining amount. The web remaining amount warning informationis, for example, message information such as “A remaining amount of theweb roll WR becomes small”. On the other hand, assume a case where theweb end determination unit 97 determines that an end of the web W isexposed on the web driven roller 71. In this case, the informationgeneration unit 98 generates web exchange request information fornotifying that it is necessary to exchange the web W, that is, it isnecessary to exchange the cleaning unit 70. The web exchange requestinformation is message information such as “Web roll WR is entirely fedout. Please exchange the cleaning unit 70” or the like, for example.

The web remaining amount warning information and the web exchangerequest information generated by the information generation unit 98 areoutputted to a notifying unit DP (FIG. 16) which the image formingapparatus 1 includes. The notifying unit DP notifies the web remainingamount warning information and the web exchange request informationoutputted from the information generation unit 98. The operator cangrasp the fact that the remaining amount of the web roll WR has becomesmall by recognizing the web remaining amount warning information whichis notified by the notifying unit DP. Further, the operator can graspthe fact that it is necessary to exchange the cleaning unit 70 byrecognizing the web exchange request information notified by thenotifying unit DP.

When the operator who recognizes the web exchange request informationinstructs execution of the exchange operation of the cleaning unit 70 atan operation unit (not shown) of the image forming apparatus 1, theseparation and contact control unit 93 moves the cleaning unit 70 to themounting and removing position by controlling the unit driving unit 80.Then, the operator pulls out the conveyance unit frame 40H forward fromthe body frame 100 of the apparatus body 10, and takes out the cleaningunit 70 from the cleaning unit mounting portion 40B of the conveyanceunit frame 40H. Subsequently, the operator mounts the new cleaning unit70 on the cleaning unit mounting portion 40B of the conveyance unitframe 40H.

In the present embodiment, when the cleaning unit 70 is removed from theapparatus body 10 integrally with the conveyance unit frame 40H, a partof the drive transmission system between the rotation drive unit 75K andthe pair of rotary levers 454 (the engagement between an apparatus body10 and the unit drive output gear 805) is disconnected. As a result, thepair of rotary levers 454 becomes rotatable about the rotary shaft 451.Accordingly, when the operator removes the old cleaning unit 70 from thecleaning unit mounting portion 40B, the pair of rotary levers 454 canrotate so as to send out the cleaning unit 70 to the outside of thecleaning unit mounting portion 40B. In other words, the pair of rotarylevers 454 rotates about the rotary shaft 451 so as to assist theremoval of the pair of unit fulcrum pins 70P of the cleaning unit 70from the pair of pin receiving portions 454P. As a result, the operatorcan easily remove the pair of unit fulcrum pins 70P of the cleaning unit70 from the pair of pin receiving portions 454P. Accordingly, thecleaning unit 70 can be easily removed from the conveyance unit frame40H of the belt conveyance unit 40.

The cleaning device 7 and the image forming apparatus 1 including thecleaning device 7 according to one embodiment of the present disclosurehave been described above. With such a configuration, paper dust, ink,and the like can be removed from the resist lower roller 32 withcertainty, and can be collected on the web W. Accordingly, the resistlower roller 32 can be properly cleaned. Accordingly, it is possible tosuppress the occurrence of conveyance failure of the sheet S and theoccurrence of stains such as ink on the sheet S and hence, the imageforming apparatus 1 can form a proper image.

The present disclosure is not limited to the above embodiment, and thefollowing modified embodiments can be adopted.

In the above-described embodiment, the description has been made withrespect to the mode where the web W is separated from and brought intocontact with the resist lower roller 32 by changing the position of thepressing roller 72 with respect to the resist lower roller 32 along withthe movement of the cleaning unit 70. However, the present disclosure isnot limited to such a mode. For example, the configuration may beadopted where the pressing roller 72 is disposed in a vertically movablemanner, and the web W is separated from and is brought into contact withthe resist lower roller 32 by moving the pressing roller 72.

In the above-described embodiment, the description has been made usingthe resist lower roller 32 as the conveyance roller to be cleaned by thecleaning unit 70. However, the conveyance roller may be another rollerwhich conveys the sheet S.

Further, in the above-described embodiment, the description has beenmade with respect to the mode where the image forming unit 50 is formedof an ink-jet-type image forming unit. However, the image forming unit50 may be formed of an image forming unit which adopts another imageforming method such as a publicly known electrophotographic method.

According to the present disclosure described above, it is possible toprovide a cleaning device capable of cleaning a surface of a conveyanceroller which conveys a sheet for a long period using a rolled bodyformed of a web having a limited length, and an image forming apparatusprovided with the cleaning device.

Although the present disclosure has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present disclosurehereinafter defined, they should be construed as being included therein.

The invention claimed is:
 1. A cleaning device capable of cleaning asurface of a conveyance roller that is rotatably supported on anapparatus body of an image forming apparatus and is configured to conveya sheet, the cleaning device comprising: a strip-shaped web configuredto clean the surface of the conveyance roller by being brought intocontact with the surface of the conveyance roller; a support rollerconfigured to support a rolled body formed of the web; a take-up rollerconfigured to be rotatably driven and to take up the web while pullingout the web from the support roller; a pressing roller configured to bebrought into contact with the web between the support roller and thetake-up roller, and configured to press the web to the conveyanceroller; a separation and contact mechanism configured to separate theweb from the conveyance roller and to bring the web into contact withthe conveyance roller by changing a position of the pressing roller withrespect to the conveyance roller; and a controller configured to controlcleaning of the conveyance roller by the web, wherein the controllerincludes: a conveyance state determination unit configured to determinewhether the conveyance roller is in either a sheet conveyable state or asheet non-conveyable state; a separation and contact control unitconfigured to control the separation and contact mechanism so as toallow the web to be pressed to the conveyance roller by the pressingroller when the conveyance roller is in the sheet non-conveyable state;a conveyance roller rotation control unit configured to rotate theconveyance roller in a state where the web is pressed to the conveyanceroller; and a take-up control unit configured to allow the take-uproller to perform a take-up operation of taking up the web by rotatablydriving the take-up roller plural times at a predetermined time intervalwithin a cleaning time set in advance in a state where the conveyanceroller is being rotated.
 2. The cleaning device according to claim 1,wherein the take-up control unit is configured to perform: monitoringprocessing for monitoring a cumulative value of a number of times of thetake-up operation; operation number setting processing for setting anumber of times of the take-up operation performed within the cleaningtime corresponding to the cumulative value such that a total take-upamount of the web taken up by the take-up roller due to the take-upoperation performed plural times becomes constant within a predeterminedallowable range; and take-up processing for allowing the take-up rollerto perform the take-up operation the number of times set by theoperation number setting processing within the cleaning time.
 3. Thecleaning device according to claim 2, wherein the take-up control unitis configured to allow the take-up roller to perform the take-upoperations the plural time at equal time intervals in the take-upprocessing.
 4. The cleaning device according to claim 1, wherein theconveyance roller rotation control unit is configured to continue therotation of the conveyance roller within a predetermined rotationcontinuation time from a point of time of the end of the cleaning time,and the separation and contact control unit is configured to control theseparation and contact mechanism so as to separate the web from theconveyance roller within the rotation continuation time.
 5. An imageforming apparatus, comprising: an apparatus body; a conveyance rollerconfigured to be rotatably supported on the apparatus body and to conveya sheet; an image forming unit configured to form an image on the sheet;and the cleaning device according to claim 1 configured to clean theconveyance roller.